FS#1474 - Dimension > Leader: changing options breaks tool

Community 3.15.5.3 (Git 9c49f08b), FreeBSD 10.3, Qt 5.5.1

Start the Dimension Leader tool, click a point. While the rubber line is active, click the “Arrow head” option to toggle it (the effect is seen on the rubber line immediately). Now click it again to toggle. The entire dimension disappears with no appreciable trace left anywhere. The DL tool stays active.

Expected outcome would be for the dimension to just toggle the arrow head style.

This only seems to happen if this double-toggling is done as long as no segment is actually created yet (i.e. once at least one segment is actually set, the repeated toggling works as expected).